Hounds' history: Has bow-wow bondage ended?

Q.If dogs wrote their own history, when would they say the epoch of dog-bondage ended? ­R. Tin Tin

A. Not until the invention of mechanical and electrical motors, say psychologist Stanley Coren and Janet Walker in What Do Dogs Know? Many dogs had been specifically bred as a compact source of cheap power, like the long-bodied, short-legged "turnspits"– kept in enclosed wheels where their walking turned meats roasting over a fire. "A house might have several turnspits, and each might be required to work the wheel for a number of hours."

The dogs also churned butter, ground grains, pumped water. There was even a patent for a dog-driven sewing machine. On Sundays, turnspits were taken to church and used as foot-warmers. One time, note Coren and Walker, a bishop was quoting from the Book of Ezekiel: "It was then that Ezekiel saw the wheel." At the mention of the word "wheel," the dogs reportedly "clapt their tails between their legs and ran out of the church."

Q.Your brainy girlfriend challenges: "Lover, I'll consider your marriage proposal if you pitch it to me at exactly 12am or 12pm New Year's Day, you choose which one. But I'll accept only if you pick correctly from these two times." Is this going to be your lucky year? ­E. Taylor

A. Better smart than lucky because proposing at 12am is not possible since there is no such thing as 12am, as explained by the Time and Frequency Division of the National Institute of Standards and Technology.

"A.m." and "p.m." are abbreviations for "ante meridiem" and "post meridiem," meaning "before noon" and "after noon." Noon is neither before noon nor after noon, it is just noon; likewise, midnight is just midnight. So neither the "12am" nor the "12pm" designation is technically correct.

You could, however, get away with using either 12am or 12pm for midnight because midnight is both 12 hours before noon and 12 hours after noon, though both would be ambiguous as to the date intended. To avoid ambiguity, railroads, airlines, and insurance companies use 12:01am for an event beginning the day, 11:59pm for ending it.

Better still is the 24-hour clock's 0000 for the moment beginning the day, 2400 for the moment ending it. Note that the same moment both ends one day and begins the next.

So the brainy lady knows you'll pitch at midnight her bewitching hour– first moment of the first day of the New Year, and is eager to give you her nod. Smartly done!

Q.What is the smallest measurable unit of time? Nanoseconds– thousandths of a microsecond– are small, used often in discussions of computers, but things can get smaller still. How small? ­S. Hawking

A. Basically, no one knows if there is a smallest unit of time, says Thomas O'Brian of the National Institute of Standards and Technology. By some theories, time is endlessly divisible, units getting as small as one wishes, though measuring them would be another matter. Other theories suggest that time and space are both "quantized," with fundamentally indivisible units at the base.

Below the nanosecond (10^-9, or 0.000000001 second) are the picosecond (10^-12) and femtosecond (10^-15), the current limit to our most accurate measurement of time, or about one second out of 30 million years. Then the attosecond (10^-18): Some present-day lasers can be pulsed at about the 100 attosecond level, and researchers keep making the pulses shorter, says O'Brian.

Smaller yet are the zeptosecond (10^-21) and yoctosecond (10^-24, currently the second shortest interval with an official, internationally agreed-upon name). The Planck time, or about 10^-43 second, is the shortest, which may be the briefest possible unit of time.

At this temporal scale, says Scientific American magazine, the whole notion of time as we know it may lose its meaning.

Q.Long after the human race is gone, what legacy of ours will remain? ­W. Durant

"The Egyptian pyramids could turn to dust, be rebuilt, and turn to dust again ten thousand times over before these footprints vanish.... They will survive the human race."

Several gold-plated plaques endure alongside, placed there by Apollo crews. Should aliens ever stumble onto the scene, the prints and the plaques will greet them. And if the extraterrestrials somehow decipher the recurring letters, they will read the names of astronaut visitors and the expression, "We came in peace."